Advanced

Measuring overload effects during fatigue crack growth in bainitic steel by synchrotron X-ray diffraction

Lopez-Crespo, P.; Steuwer, Axel LU ; Buslaps, T.; Tai, Y. H.; Lopez-Moreno, A.; Yates, J. R. and Withers, P. J. (2015) In International Journal of Fatigue 71. p.11-16
Abstract
In this work we present the results of in situ synchrotron X-ray diffraction measurements of fatigue crack-tip strain fields following a 100% overload (OL) under plane strain conditions. The study is made on a bainitic steel with a high toughness and fine microstructure. This allowed a very high (60 mu m) spatial resolution to be achieved so that fine-scale changes occurring around the crack-tip were captured along the crack plane at the mid-thickness of the specimen. We have followed the crack as it grew through the plastic/residually stressed zone associated with the OL crack location. We observed two effects; one when the enhanced plastic zone is ahead of the crack and one after it has been passed. Regarding the former it was found that... (More)
In this work we present the results of in situ synchrotron X-ray diffraction measurements of fatigue crack-tip strain fields following a 100% overload (OL) under plane strain conditions. The study is made on a bainitic steel with a high toughness and fine microstructure. This allowed a very high (60 mu m) spatial resolution to be achieved so that fine-scale changes occurring around the crack-tip were captured along the crack plane at the mid-thickness of the specimen. We have followed the crack as it grew through the plastic/residually stressed zone associated with the OL crack location. We observed two effects; one when the enhanced plastic zone is ahead of the crack and one after it has been passed. Regarding the former it was found that the compressive stress at the crack-tip initially falls sharply, presumably due to the increased plastic stretch caused by the OL. This is associated with a concomitant fall in peak tensile stress at K-max, the elastic excursion between K-min and K-max remaining essentially unchanged from before OL. Subsequently discontinuous closure as seen previously for plane stress caused by crack face contact at the OL location limits the elastic strain range experienced by the crack tip and thereby retards crack growth. (C) 2014 Elsevier Ltd. All rights reserved. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Overload effect, Fatigue crack closure, Residual stress, X-Ray, diffraction
in
International Journal of Fatigue
volume
71
pages
11 - 16
publisher
Elsevier
external identifiers
  • wos:000350599100003
  • scopus:84915805286
ISSN
1879-3452
DOI
10.1016/j.ijfatigue.2014.03.015
language
English
LU publication?
yes
id
547c958b-997e-479b-9cbe-047237e38f7b (old id 5297304)
date added to LUP
2015-04-27 09:20:33
date last changed
2017-11-05 03:16:43
@article{547c958b-997e-479b-9cbe-047237e38f7b,
  abstract     = {In this work we present the results of in situ synchrotron X-ray diffraction measurements of fatigue crack-tip strain fields following a 100% overload (OL) under plane strain conditions. The study is made on a bainitic steel with a high toughness and fine microstructure. This allowed a very high (60 mu m) spatial resolution to be achieved so that fine-scale changes occurring around the crack-tip were captured along the crack plane at the mid-thickness of the specimen. We have followed the crack as it grew through the plastic/residually stressed zone associated with the OL crack location. We observed two effects; one when the enhanced plastic zone is ahead of the crack and one after it has been passed. Regarding the former it was found that the compressive stress at the crack-tip initially falls sharply, presumably due to the increased plastic stretch caused by the OL. This is associated with a concomitant fall in peak tensile stress at K-max, the elastic excursion between K-min and K-max remaining essentially unchanged from before OL. Subsequently discontinuous closure as seen previously for plane stress caused by crack face contact at the OL location limits the elastic strain range experienced by the crack tip and thereby retards crack growth. (C) 2014 Elsevier Ltd. All rights reserved.},
  author       = {Lopez-Crespo, P. and Steuwer, Axel and Buslaps, T. and Tai, Y. H. and Lopez-Moreno, A. and Yates, J. R. and Withers, P. J.},
  issn         = {1879-3452},
  keyword      = {Overload effect,Fatigue crack closure,Residual stress,X-Ray,diffraction},
  language     = {eng},
  pages        = {11--16},
  publisher    = {Elsevier},
  series       = {International Journal of Fatigue},
  title        = {Measuring overload effects during fatigue crack growth in bainitic steel by synchrotron X-ray diffraction},
  url          = {http://dx.doi.org/10.1016/j.ijfatigue.2014.03.015},
  volume       = {71},
  year         = {2015},
}